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JAMES' M. CARPENTER, 0F PWTUCKET, RHODE ISLAND.

Letters Patent No. 113,740, dated April 18, 1871.

IMPROVEMENT iN MACHINES FOR CUTTING SCREWS.

The Schedule referred to in these Letters Parent and making part of the Barnim- A accordance with those described in Letters Patent granted to me Manch 9, 1869, and I have shown my improvements as applied in connection with such dies; but some of them may also be applied to other forms ot' sectional dies or cutters not having that mode of construction.

My invention relates, in" the first placc,to the mode of constructing and arranging the dies and the devices izo-operating therewith so that the dies may be 'moved radially to enlarge or diminish the diameterl of the screw while it is being cut, or to entirely withdraw the dies from the screw so that it ma-y be rcmoved fronl the dies withoht vturning it backward, without derangng the cleanince given to the dies by rocking them npo'n the axis dr bolt by which they are attached to the die-stock. y

1n my aforesaid patent each die is represented as being mounted upon a bolt ,or axis' upon which it is rocked, to give the proper clearance to the cuttingedge and the exact size-ofthe screw to be made; and it is also, if desired, intended to be further oscillated a sufficient distance to permit the screw to be removed after it is cnt. l The last opera-tion would have to be repeated for each screw out, and as the ports are covered with the chips produced by cutting thel screws the dies would be liable to error in coming back to the correct position, and would also soon wear .loose upon their axes, bot-h of which evils would change the size of the same.

The purpose of this improvement is to remedy these evils so that the dies may be opened and closed without rocking them upon their axes and still preserve that property of adjusting the size and clearance; and /f 1t consists in the combination of each of the dies o1' cutters with a. slide or die-holder which moves radially in the die-stock, and to' which the die is attached by an axis upon which the die may be rocked, and also secured to the slide by adjustable fastenings, as will be described; and

I t also consists in the combination of' the die-stock and the slides which carry the dies, arranged radially therein, and an annular vcam-plate for simultaneously moving the slides in or out, and a, former or pattern which together control the movement ofthe dies as they pass over the screw, and thus withdraw or advance the dies, and thereby enlarge or contract the diameter ot the screw, according to the shape of the former, within the capacity ol' the dies to cut a. form varying from the cylindrical; and

It also consists in combining with the annular campiatc or its equivalent for moving the dies* and the former or its equivalent, an adjusting-screw or other equivalent means of adjusting the relation of the former to the dies, so that thereby a. succession of cuts may be taken by the dies by repeating the operation.

f My invention alsov relates to thc mechanism by which 4the pitch of the screwto be formed is accurately determined, and the' dies are relieved of the labor of dragging the die-stock and its Ieidjuncts forwnrdnnd longitudinally pls the dies form the thread, and consists in combining with the die-stock, or `with the mandrel that turns the screw instead, a leadingscrew arranged concentric with the axis of the mandrel and dies, and having n pitch coinciding with that of thcscrew tohe formed orsome multiple thereof, so that the force required to draw the die-stock along, or the mandrel that holds the screw, as the case may be, shall not be exerted by tlie thread that is being formed; but sha-ll be exerted by',the leader in aline with the axis, and so as to hold the die-stock in equilibrium.

My invention also relates to the employment of' l means for protecting the dies from the wearing produced by the scale of the iron when screws are cut whose surfaces are in tile condition in which they are left by the forging, and consists in combining with one or more'ot'the dies a scaling-tool which works in advance of the dies and removes the scale from the surface oi' the screw-blank, and can be readily removed and replaced to sharpen the same without disturbing the dies.

Description.

In the drawing- Figure 1 is a. plan of the machine.

Figure 2 is a side elevation.

Figure 3 is an end elevation showing the face of the die-stock and its connections. l

Figure 4 is a. transverse sectional elevation looking toward the back of the die-stock.

The mechanism herein shown and described is designed to be used in connection with the head-stock and hed ot' a. common lathe, the mandrel ot" which is provided with means for holding and lturning the screw to be cut, and is especially adapted to cutting taps both tapering and straight, or with a short portion only of the point tapered, in which cases, :is well which slides buck and forth' lili'e thc back center of a lathe, the mechanism for moving which is not shown.

The inner end ofthe'mandrel B extends a considera-ble distance from the standard, and upon this part carries the die-stock U and its accessory parts, which slide lengthwise upon it.

AtA the cxtreme end it carries a back-center, C, so that the screw to he cut can be suspended upon centers if desired, as in a common lathe.

The partof the mandrel B that is between the. standards A', carries a sleeve, B, which is formed with a screw upon its surface of the same pitch as the screw to be cut, or some multiple thereof, which serves as a leader to carry the die-stock along, as will be described. A

The sleeve B is revolved coincidently with the main arbor of the head-stock by means ol' the gear Bl, which is connected therewith b va shaft and a train of gearing, not shown.

The die-stock O has along hub or sleeve, which is nicely fitted to the mandrel B, and is of a sucient length to allow the longitudinal inovemeut ot' the die-stock 'upon themandrel required to cut the screw.

The outer part of thel die-stock is of a disk-like form, iu the outer part of which radial recesses or grooves are formed in which the slides or die-holders D work, to which the several segmental dies E are attached by the bolts F, a's shown. These dies are substantially such as are described in my aforesaid patent of March 9, 1869. f

The dies E are slightly rocked to give the proper clearance to thcr cutting-edges,l by the adjustingscrews-G working through lugs upon the holders D, as is shownin tig. 3.

Upon the outside of the die-stock O is fitted the cam-plate H,wliich embraces both the periphery and the hub of the die-stock, and oscillates upon it.

At those points in the circumference which correv spond with 'the holders'D, it is provided with cams or inclincs D, and grooves D2, in 'which the slide-blocks I work, eachof which is connected by a rule-joint with the 'outer 'end of one of the holders D, as is shown; v'

V `By this construction thc dies are moved in or out, and'held in'pcsition by the cam-plate with great accuracy and firmness.

'lo the lmb ot' the cam-plate a handle, Jis attached to oscillate it by the hand of the operator when it is required to open the dies, and the lever J' is also attached tothe hub upon the opposite side, in the outer end of' which is the adjusting-screw K', the point of which rests upon the pattern or former L, which determines the taper to be given to the screw that is being cnt.

The pattern L is of the proper form to give the cam-plate H such a rotary movement as will impart the necessary radial movement to the dies,'and is attached to a bracket on the flame A, as shown, so that it can be readily changed when desired.

To the back end ofthe die-stock G a cross-head, O, is attached, to the arms of which two parallel rod`s\M M are fitted, which wol-l;- through guides in the standard A', as is shown. v

'lhe otherends of therods Mare also fitted into the cross-head N, which is provided with a long sleeve, N', which slides upon the leading-screw B. Ilhis arrangement allows the dic-stock O and its attachments to slide lengthwise on the mandrclB and steadies it,.

and at the samc time prevents the die-stock from turning :with the screw.

O is a. lever which hangs upon one of thcrrods )L as :L fnlcrum, and is provided with a segment of a nut, which, when the lever is raised engages with the leading-screw B'i and carries thc dic-stock and its connections forward.

The lever 0 is held at the opposite side of the leading-screw between the cross-head N and a lug, l?, upon one ofthe guide-mds, as is shown'in lig. 1.

R It are t-he stocks or holders for the scaling-tools, which are attached to two opposite dies or their hohlers, each of which carries a. scaling-tool, S, which is inserted in'a socket and held therein by a set-screw, S'. The scaling-tools arc Set so as to remove the surface of the screw-blank, und can be removed, sharpened, and replaced without disturbing the dies, in an obvious manner.

The operation of the machine inY cutting a tap, for instance, is as follows:

The tap is placed upon the centers so as to be turned by the main arbor, as in a lathe, and the camplate is turned by thc operator by the handle J, until the end of the screw K rests upon the former L. The lever O is then raised, which brings the segment of the nut that it carries into engagement with the leading-screw B2, which carries the die-stock and dies forward over the screw-blank.

As the die-stock and its connections move forward, the operator holds the lower end ofthe screw K firmly upon the former L, so that the screw slides along its upper surface. 'L hc former in this case is inclined to the axis of the lathc so as to cut a tapering screw, thereby turning the cam-'plate backward as the diestock moves forward, which, by means of the connections described, draws the dies back and gradually enlarges the diameter of the screw to the desired extent.

If a tapering point only is required, with the tap made cylindrical, the former is made with the first part only inclined. with the remainder of the surface lmade straight and set parallel with the axis of the ath'e.

When tbe dies have passed over the screw'the camplate is turned back by thc handle vJ, which opens the dies, and the lever O is lowered, which discngages the die-stock from the leader. The die-stock is then slid back to the position to remove the screw and receive another screw-blank.

In cutting ordinary screws, it will generally be found sufficient to run the dies once over the blank to form the thread; but it' greater nicety is required,- as for instance in cnttingvtapsfa second or third cut maybe taken by turning the adjusting-screw K backward a little at each cnt, which allows the cam-plate to turn a little further forward and carry the dies further toward the center, in an obvious manner.

The details of this mechanism may be considerably modified without departing from the mode of operation ofthe mechanism herein described, and I have already devised several other forms of construction; vbut that herein shown I have used with perfect success, and I have therefore represented it as a complete embodiment of my invention.

Instead of using Ithe oscillating cam-plate to move the dies, and a former to move the cam-plate, separate similar-1 cams may be 'applied directly to each die,

each made of such form as to give .the same movemeut to the dies that the former gives through the cam-plate, as herein shown. I llrst proposed to use ing more durable and moro convenient ln changing the form of the screwto bc lnnd.

by which the dies can be mov radially under the which work in a direction parallel to the axis, and are this form, but I deem thc one shown the best, as he- Other similar modlllcutloul mg-obvlously bo made t control of the former, in cutting the screw, which is the fundamental principle of my invention.

The use of scaling-tools, also, is not limitedto dies constructed and operating as is herein described, but they may be used with the same beneficial result in connection with any of the various forms of dies in common use.

1. rEhe combination of the die-stock, the dies, two or more, capable of moving radially therein, as described, andthe rotating cam-plato and cams or their equivalent, for moving the dies simultaneously, and the former or pattern for impartin said movement as the dies pass lengthwise over the screw to form the threads, substantially as described. v

2. The combination of the die-stock, the radially-V moving slides, the pivoted dies or cutters ,and mechanism, substantially as described, for adjusting said cutters. v

3. The combination of la die-stock, two or more multi-threaded dies arren ed radially in said stock, and aleading-screw and m able nut to connect therewith, the threads of said screw und nt corresponding in pitch to the pitch of the die-threads, substantially as described.

4. The adjusting-screwK or its equivalent, iu combination with the former and the devices that move the dies or cutters mdially,.snbstantially as described.

5. In combination with the die-stock and multithreaded dies, the scaling-tool, substantially as described.

Executed January 20,-A. D. 1871.

, JAMES M. CARPENTER.

. Witnesses:

" WAL'O. Hmmm),

lif. O. Lomnno.. 

